Effects of chunk breakage and surface protective film on negative difference effect of magnesium alloys

Lee, Choong Do; Kang, Choon Sik; Shin, Kwang Seon

doi:10.1007/bf03186084

Cited by 12 publications

(6 citation statements)

References 15 publications

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“…This possibly explains the findings of Dietzel et al [ 22 ] and Weber et al [ 6 ], where the HER in pits is much higher than at the surface. Lee et al [ 23 ] tried to interpret the NDE by a chunk breakage and the creation of a protective film at the surface, but they did not explain how the surface film is chemically composed. Beside the difficulties in explaining NDE, the calculation of the corrosion rates of Mg based on I vs. E curves using the Tafel kinetic is not reliable.…”

Section: Literature Surveymentioning

confidence: 99%

The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys

Müeller

Hornberger

2014

IJMS

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Mg and Mg alloys are becoming more and more of interest for several applications. In the case of biomaterial applications, a special interest exists due to the fact that a predictable degradation should be given. Various investigations were made to characterize and predict the corrosion behavior in vitro and in vivo. Mostly, the simple oxidation of Mg to Mg2+ ions connected with adequate hydrogen development is assumed, and the negative difference effect (NDE) is attributed to various mechanisms and electrochemical results. The aim of this paper is to compare the different views on the corrosion pathway of Mg or Mg alloys and to present a neglected pathway based on thermodynamic data as a guideline for possible reactions combined with experimental observations of a delay of visible hydrogen evolution during cyclic voltammetry. Various reaction pathways are considered and discussed to explain these results, like the stability of the Mg+ intermediate state, the stability of MgH2 and the role of hydrogen overpotential. Finally, the impact of MgH2 formation is shown as an appropriate base for the prediction of the degradation behavior and calculation of the corrosion rate of Mg and Mg alloys.

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Section: Literature Surveymentioning

confidence: 99%

The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys

Müeller

Hornberger

2014

IJMS

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“…It is important to mention that short-term corrosion resistance measurements (i.e. electrochemical measurements) may lead to confusing conclusions about the behavior of magnesium alloys [63], since these alloys exhibit a special electrochemical phenomenon known as the negative difference effect (NDE) and this increases with the content of Al in the Mg alloy [66]. This effect could introduce significant errors into corrosion rate measurements when using electrochemical techniques.…”

Section: Corrosion Testsmentioning

confidence: 99%

New insights on the influence of low frequency pulsed current on the characteristics of PEO coatings formed on AZ31B

Toro

Zuleta

Correa

et al. 2020

Mater. Res. Express

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In this work, anodic oxide layers on the surface of an AZ31 magnesium alloy were obtained by plasma electrolytic oxidation (PEO) process under low frequency pulsed current. For this, electrolytical solutions containing hexamethylenetetramine and sodium fluoride were used. The morphology and chemical composition of formed coatings were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Also, salt spray test, hydrogen evolution and electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy) were conducted in order to study the corrosion behavior of the coated samples. It was found that the use of low frequency pulsed current for the PEO process reduces the film porosity and increases its thickness, compared with PEO films obtained by continuous anodization. The effect of the pulsed current signal was also analyzed for a two steps PEO process, observing changes in the morphological characteristics of the coatings which allow a better corrosion according electrochemical tests (short term corrosion measurements). However, long term tests results as hydrogen evolution and salt spray tests, indicated the opposite. Both the film porosity and thickness were affected by either the pulsing of the current or the use of a two-step process.

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“…In recent years, the modification of alloy composition and/or heat treatment has been attempted for improved mechanical properties [4][5][6][7][8][9][10] and corrosion resistance [11][12][13][14][15] in the Mg casting alloys. However, there is a growing need for high strength wrought Mg alloys in the automotive and aerospace industries.…”

Section: Development Of Wrought Magnesium Alloysmentioning

confidence: 99%

Processing and Characterization of Magnesium Alloys

Jung

Shin

2005

MSF

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Magnesium has the lowest density among the commercially available structural metals and its superior physical and mechanical properties make magnesium alloys extremely attractive for applications requiring lightweight, good castability and damping capacity. In recent years, due to the demand for lightweight magnesium components in the automobile and electronic industries, the world market for magnesium alloys has increased rapidly. At the same time, the research activities on manufacturing process and characterization of magnesium alloys have also increased significantly. The research activities have been concentrated on many different fields, including the development of high pressure die casting process and semi-solid processing, development of high strength wrought alloys and components, and characterization of microstructure, mechanical properties as well as corrosion properties. In this article, the recent progresses achieved in these research areas at Seoul National University will be introduced.

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Effects of chunk breakage and surface protective film on negative difference effect of magnesium alloys

Cited by 12 publications

References 15 publications

The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys

The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys

New insights on the influence of low frequency pulsed current on the characteristics of PEO coatings formed on AZ31B

Processing and Characterization of Magnesium Alloys

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